I don't see how a roofer could give you an opinion on a roof without seeing it. I'd contact some of the roofers below to check it out.
You can be creative....it just depends on how much you want that particular home, and figuring out how to make it work.
Once again, Good Luck!
I agree, in my 36 year career as a Realtor, I have never seen a shake roof (unless the roof was very thick, Old Growth cedar) be able to be certified after that many years. I have been told by roofers that most shake roofs are good for 20 years.
On the other hand, I have used Dwayne (owner of Heritage Roofing) at 425-508-6788, for many years and he has always done an outstanding job, not to mention almost always beats anyone else's bid.
Chris Brown with Bruce's Shakemill roofing (206-349-9307) is the best roofer I have used in my 30 years in the business. He and his Dad used to own Brown's Golden Rule Roofing and they specialized in roof certs and maintainence contracts. Bruce's not only does a fabulous job but has been lower in price by far than competitors. They have a huge crew and will usually have most roofs done in a day. Most buyers are now electing to replace shake with high quality composition.
The underwriter will probably require that the roof will be replaced as a condition for approving financing. I had this happen and the roof was replaced during escrow and paid from the proceeds of the sale by the seller. The buyer selected the color, type, etc.